Low voltage neon indicator light



June 26, 1962 G. I. WILLIAMS ETAL 3,041,499

LOW VOLTAGE NEON INDICATOR LIGHT Filed NOV. 7, 1960 20 12 10 fif x INVENTORS 6224a: I. W'ILZIIAMJ;

A T TOR/V5 Y 3,041,499 LOW VOLTAGE NEON INDICATOR LIGHT Gerald I. Williams, Minneapolis, and Robert E. Wessluntl, St. Paul, Minn., assignors to Transistor Electronics Corporation, Minneapolis, Minn., a corporation of Minnesota Filed Nov. 7, 1960, Ser. No. 67,529 12 Claims. (Cl. 315-435) This invention relates to low voltage indicating lights and more particularly to an improved low voltage indicator light utilizing a neon bulb.

Indicator lights have been well known and used in connection with electrical equipment both for signal indication purposes and for indicating various conditions of operation of electrical equipment. On low voltage applications, and in particular in connection with direct current power supplies or signal sources, the indication lamp required would be of the incandescent type and would normally present a certain power drain to the associated equipment. This type of apparatus normally has limited life and requires regular maintenance. Neon indication lamps are normally restricted to high voltage alternating current or direct current applications since high voltage types of power supplies are necessary to fire or energize the neon bulb. Such an indicator type does, however, have the desirability of low current drain and long life, eliminating maintenance problems and increasing reliability in operation. Where this type of indicating light is applied to low voltage direct current battery type power supplies, it has always required rather complex and expensive power conversion equipment to operate the lamp.

The present invention is directed to an improved indicating light or lamp which includes as part thereof power conversion equipment to provide a complete selfcontained indicating unit suitable for application to low voltage direct current power supplies. It is therefore an object of this invention to provide an improved indicating light for direct current low voltage equipment.

Another object of this invention is to provide an indicating light which is small and compact and has an exceptionally long life and low current drain.

A further object of this invention is to provide an improved indicating light which utilizes circuitry permitting the use of a neon bulb to give long life and which is applicable to low voltage operation.

Another object of this invention is to provide an indicating light of this type which may be operated by signal sources a part of the energization thereof.

It is also an object of this invention to provide in an indicating light of this type improved circuitry to prevent overheating of the transistor oscillator.

These and other objects of this invention will become apparent from the reading of the attached description together with the drawings wherein:

FIG. 1 is a plan view of the improved indicator light,

FIG. 2 is a plan view of the indicator light with the casing removed to disclose the arrangement of parts,

FIG. 3 is a bottom view of the indicator light of FIG. 2 showing the circuit conductors,

FIG. 4 is a schematic circuit of one embodiment of the improved indicator light,

FIG. 5 is a schematic circuit of the second embodiment of the improved indicator light.

Our improved indicator light is shown in plan view in FIG. 1 as including an opaque casing which is cylindrical in form and has a reduced diameter portion 12 which is threaded as at 13 with a clear or transparent closed end tip 15 integral therewith or suitably secured thereto. The casing is open at its opposite extremity and normally has a securing nut on the threaded por- 3,941,499 Patented June 26, 1962 tion 13 designed to clamp the lamp into an aperture in the enclosure or panel of the device (not shown) upon which the indicating lamp is to be mounted. Extending from the open end of the casing are a plurality of terminals 21, 22 by means of which a power supply'may be connected to the indicating light. Two such terminals are shown in FIG. 1 to indicate one embodiment or version of the indicating lamp while in FIGS. 2 and 3 a third terminal is included, indicated as 24, to indicate a second circuit embodiment of the lamp.

FIGS. 2 and 3 show the indicating lamp With the cover or casing 10 removed to disclose the arrangement and connection of parts. It will be seen in FIG. 2 that the parts are all mounted on a supporting base or support structure, indicated at 25, which is made of insulating material, such as a suitable plastic. Base 25 is rectangular in form and extends along the extent of the casing 10. Positioned at one extremity of the base or support 25 is an insulating disc or terminal support 26 in which the terminals 21, 22, and 24 are positioned, the disc being held in position relative to the support through suitable means such as the electrical connections between the terminals and parts, or if desired, through mechanical con necting means. In FIG. 2 the terminals extend through the disc and are connected directly to a plurality of resistor elements indicated generally at 30 which will be later specifically identified in connection with the circuit. It has been found that sufiicient strength and rigidity exists between the electrical connections of the resistors to the terminals and to the board to provide strength of mounting of the disc 26 to the support or base 25 eliminating further mechanical connections therebetween. The disc 26 is of sufiicient diametrical dimension to fill the open end of the casing '10 and would be normally secured thereto through suitable sealing mean-s (not shown).

Also included on the support and suitably secured thereto are a transistor indicated generally at 32, a core indicated at 35 which is connected to the board through a suitable means indicated at 36, a condenser indicated at 37, a resistor indicated at 38, and a neon glow bulb 40 which is connected through its electrodes to the base member 25 and is positioned to extend along the axis of the support.

As will be seen in FIG. 1 when the support with the transistor, core and bulb together with the associated resistors and condensers are positioned within the casing 10, the bulb will be located adjacent the transparent portion 15 of the casing to provide for indication from the bulb.

The bottom view of the support, as shown in FIG. 3, discloses circuit conductors indicated generally at 45, between the various elements mounted on the upper surface of the board, these conductors being printed on or suitably connected to the support to be integral therewith. The solder connections between the conductors and the resistors, as well as the various other elements of the circuits, provide a complete electrical circuit as well as mechanical connection between the parts. As will be later seen the core 35 encloses and houses an inductance coil and a transformer winding which make up the oscillator portion of the circuitry for the indicating lamp.

In FIG. 4 an embodiment of the indicating light is shown which is suitable for application directly to a low voltage power supply, for indication of power on or power off without auxiliary control. In this embodiment of the apparatus, the transistor 32 is of the PNP type, and the power supply can be either a negative or positive polarity direct current of approximately 12 to 24 volts. This embodiment of the indicator light includes a first circuit extending from terminal 21 through a conductor 50, a conductor 51 to a portion 52 of a winding 53 and from a tap connecting said transformer winding across a second resistor and said glow bulb; third circuit means including a third resistor connected to saidone of said terminals and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit, fourth circuit means including a diode connected between said transistor base electrode and saidfirst resistor; said first, second, third and fourth circuits including conductors positioned on and included as a part of said support; and casing means having a transparent closed extremity, said casing means being mounted to enclose said support with said bulb positioned adjacent said transparent extremity and joined to said disc. 7 v

6. In an indicator light, an elongated support, a transistor having collector, emitter and base electrodes and mounted on said support; a transformer winding and an inductance enclosed by a common core and connected to said support; a glow' bulb mounted on said support at one extremity thereof and extending along the axis of said support, disc means including a plurality of terminals mounted on the other end of said support; first circuit means extending from one of said terminals through a portion of said transformer Winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to another of said terminals to provide an oscillator circuit adapted to be connected to a source of power; second circuit means connecting said transformer winding across a second .resistor and said glow bulb; third circuit means including a resistor connected to said one of said terminals and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit; fourth circuit means including a diode connected between said transistor base electrode and said first resistor; fifth circuit means connected from a third of said terminals through a bias resistor to said base electrode and operative when energized with a predetermined electrical signal to turn on and off said light; said first, second, third, fourth and fifth circuits including conductors positioned on and included in part of said support; and casing means being mounted to enclose said support with said bulb positioned adjacent at transparent extremity and said casing means joined to said disc means.

7. In an indicator light, a transistor including an emitter, collector and base electrodes; a transformer winding and an inductance winding positioned within and enclosed by a common core, a glow bulb, first circuit means including terminal means connected through a portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to provide a blocking oscillator circuit adapted to be connected to a source of power; second circuit means connecting said transformer winding across a second resistor and said glow bulb; third circuit means including a third resistor connected to one of said terminal means and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit; and fourth circuit means includinga diode connected between said transistor base electrode and saidfirst resistor to provide a low impedance circuit around said transitor and said inductance winding.

8. In an indicator light: an elongatedsupport, a transistor including emitter, collector and base electrodes mounted on said support; a tranformer winding and an inductanee Winding magnetically associated with a common core mounted on said support; a neon bulb mounted on said support and extending along the axis of said support; terminal means including a plurality of terminals mounted on the other end of said support; first circuit means extending from one of said terminals through a portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to another of said terminals to provide a blocking oscillator circuit adapted to be connected to a source of power; second circuit means ('5 connecting said transformer winding across a second resistor and said neon bulb; third circuit means including a third resistor connected to said one of said terminals and the base electrode of said transistor" to provide a biasing circuitfor said oscillator circuit, and fourth circuit means including a diode connected between said transistor base electrode and said first named resistor.

9, In an indicator light, a transistor including emitter, collector and base electrodes; a transformer winding and an inductance winding positioned within and enclosed by a common core, a glow 'bulb,; fir;st circuit means including terminal means connected through a portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to provide a blocking oscillator circuitadapted to be connected to a source of pow??? second circuit means connecting said transformer winding across a second: resistor andsaid glow bulb; third circuit means including a third resistor connected to one ofsaid terminal means and the base electrode of said transistor to provide a biasing circuit forsaid oscillator circuit; fourth circuit means including a diode connected between said transistor base electrode and said first resistor to provide a low impedance circuit around said transistor and said inductance winding, fifth circuit means connected from a third of said terminals through a bias resistor to said base electrode and operative when energized with a predetermined electrical signal to turn on and off said bulb.

10. In an indicator light, a transistor including emitter collector and base electrodes; a transformer winding and an inductance winding magnetically associated with a common core, a glow bulb, first circuit means including terminal means connected through a primary portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to provide a blocking oscillator circuit adapted to be connected to a source of power; second circuit means connecting a second portion of said transformer winding to said glow bulb; third circuit means including a second resistor connected to one of said terminal means and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit; fourth circuit means including a diode connected between said transistor base electrode and said first resistor to provide a low impedance circuit around said transistor and said inductance winding.

11. In an indicator light, an elongated support, a transistor including emitter, collector and base electrodes mounted on said support, a winding. and an inductance coil magnetically associated with a common core on said support, a glow bulb mounted on said supportat one extremity thereof, terminal means including a plurality of terminals mounted on the other end of said support, first circuit means extending. from a first of said terminals through a portion of said winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance coil to another of said terminals to providean oscillator circuit adapted to be connected to a source of power, second circuit means connecting said winding to said glow bulb in a step up' transformer circuit, third circuit means including a bias resistor connected to said first terminal and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit, and fourth circuit means including a diode connected between said transistor base electrode and said first resistor.

12. In an indicator light an elongated support,- a'tran port; terminal means including a plurality of terminals mounted on the other end of said support; first circuit turn on again. This will cause a current output through the primary portion of the auto transformer to provide a step-up voltage sutficient to fire or ignite the indicator light 40. The condenser 37 filters and smooths current flow through the neon bulb to provide a voltage to maintain the bulb 40 ignited or energized. Diode 70 is connected around the inductance 61, resistor 62 and a portionof the transistor to provide a bleed path to limit current flow in thetransistor and prevent overheating of the same, thereby improving the life of the apparatus. This circuit embodiment permits control of the indicator light from an auxiliary high impedance signal. Further, the output of the auto transformer is fed through the filtering circuit sufficient to maintain a high indication or glow-of the neon bulb.

It will be seen that our improved indicator light includes a self-contained current converter or modulator permitting the indicator light to be operated from a direct current source and including further a step up transformer to provide sufiiciently high voltage to ignite a neon type bulb from a low voltage source. The apparatus is all mounted on a printed circuit base with a terminal assembly connected thereto such that it may be housed in a ca'sing with the bulb positioned adjacent to a portion of the casing to give indication therethrough.

It will be recognized that certain changes may be made the shape and type of its components, and hence we wish our invention to be limited only by the scope of the appended claims.

' What is claimed is:

1. In an indicator light: an elongated support, a transistor including emitter, collector and base electrodes mounted on said support; a transformer winding and an inductance winding positioned within and enclosed by a common core connected to said support; a neon bulb mounted on said support and extending along the'axis of said support; terminal means including a plurality of' terminals mounted on the other end of said support; first circuit means extending from one of said terminals through a portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to another of said teminals to provide a blocking oscillator circuit adapted to be connected to a source of power; second circuit means connecting said transformer winding across a second resistor and said neon bulb; third circuit means including a third resistor connected to said one' of said circuit means including a diode connected between said transistor base electrode and said first named resistor; said first, second, third andfourth circuits including conduc- 'ing and an inductance winding positioned within and enclosed by a common core connected to said support,

a neon bulb mounted on said support and extending along the axis of said support, an annular terminal support including a plurality of terminals mountedon the other end of said support, a first circuit means extending from one of said terminals through. the primary portion of said auto transformer. winding to the collector electrode of said transistor andfrom the emitter electrode through 'a first resistor and saidinductance to another of said terminals to provide a blocking oscillator circuit adapted to be connected to a source of power, second circuit means con-' necting the secondary portion of said auto transformer winding across a second resistor and said neon bulb, third circuit means including a third resistorconnected'to said first terminal'and the base electrode of said transistor to' provide a biasing circuit for said oscillator circuit, fourth circuit means including a diode connected between said transistor base electrode and said first resistor, said first, second, third and fourth circuits including conductors printed on said support, and cylindrical casing means having an opaque body with a transparent closed extremity fitted over said support such that said bulb is'positioned adjacent said transparent extremity and the casing is joined with the said terminal support to enclose said light.

3. In an indicator light, an elongated support, a transistor including emitter, collector and base electrodes mounted on said support, a winding and an inductance coil positioned within a common core and mounted on said support, a glow bulb mounted on said support at one extremity thereof, circular terminal means including a plurality of terminals mounted on the other end of said support, first circuit means extending from a first of said terminals through a portion of said winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance coil to another of said terminals to provide an oscillator circuit adapted to be connected to a source of power, second circuit means connecting said winding across a second resistor and said glow bulb in a step up transformer circuit, third circuit means including a third resistor connected to said first terminal and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit, fourth circuit means including a diodeconnected between said transistor base electrode and said first resistor, said first, second, third and fourth circuits including conductors integral with said support, and means encasing said support having an opaque body with a transparent extremity such that said bulb is positioned adjacent said transparent extremity and the encasing means is joined to the said terminal means to enclose said light.

4. In an indicator light, anelongat-ed support, a transistor including emitter, collector and base electrode mountedfon said support, a tapped winding and an inductance winding associated with a common core connected to saidsupport, a glow bulb mounted on said support at oneextremity thereof, terminal means including a plurality of terminals mounted on the other end of said support, first circuit means extending from one of said terminal through a portion of said tapped winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and said inductance to another of said terminals to provide an oscillator circuit adapted to be connected to a source of power, second circuit means connecting said entire tapped Winding across a secondre'sistor and said glow bulb, third circuit means including a third resistor connected to said one of said terminals and the base electrode of said transistor to pro vide a biasing circuit for said oscillator circuit, fourth circuit means including a diode connected between said transistor base electrode and said, first resistor, said first, second, third and fourth circuits including conductors integral with said support, and means encasing said support having an opaque body with a transparent extremity with said bulb positioned adjacent said transparent extremity and the encasing means joined to the said terminal means to enclose said light.

' 5 In an indicator light, an elongated support; a transistor having collector, emitter and base electrodes mounted on said support; atransformer winding and an inductance enclosed on a common core and connected to said support; a glow bulb mounted on said support at one 7 portion of said transformer Winding to the collector electrode of said transistor and'from the emitter electrode through a first resistor and saidinductance to another of said terminals to provide an oscillator circuit adapted to,

be connected to a source of power; second circuit means 8 means extending from one of said terminals through a portion of said transformer winding to the collector electrode of said transistor and from the emitter electrode through a first resistor and inductance to another of said terminals to provide a blocking oscillator circuit adapted to be connected to a source of power; second circuit means connecting said transformer Winding across a second resistor and said neon bulb; third circuit means including a third resistor connected to said one of said terminals and the base electrode of said transistor to provide a biasing circuit for said oscillator circuit and 10 fourth circuit means including a unidirectional variable impedance circuit element connected between said transistor base electrode and said first named resistor.

5 References Cited in the file of this patent UNITED STATES PATENTS 2,896,124 Brown July 21, 1959 2,930,989 Krieger Mar. 29, 1960 10 2,982,881 Reich May 2, 1961 

